It is frequently necessary in the construction of panel doors, cabinet carcasses, wooden I-beams, and the like to seat the edge of a panel made of plywood, pressed board, or the like into a groove in another wooden body that can serve as a support beam or frame. Once the groove has been formed in the support member, it is standard just to apply glue to the panel edge and then fit it into place. Some fasteners such as nails may be applied across the joint to further secure it together.
Such a procedure does not produce a very strong joint between the two pieces unless done with great care. Furthermore the joint can be messy, in particular when any fasteners are not carefully seated and covered.